1. Field of the Invention
This invention relates to pharmaceutics for mucosal administration of pharmacologically active peptides or proteins, which exhibit excellent mucosal absorbability.
2. Description of the Related Art
Administration of pharmacologically active peptides or proteins has heretofore been normally effected by injection means, for the reasons that oral administration results in poor drug absorption and their decomposition and deactivation in the digestive tract. However, administration by injection is painful and involves risks of inducing amyotrophia (muscle atrophy) or other diseases. There is also a problem of inconvenience for the patients who need to attend hospitals to be injected.
In the recent years, a variety of methods for administering peptides or proteins to replace injections are being tried, such as the administration to the rectum, vagina, nasal or oral mucosa. These mucosal administration means have the advantages of preventing deactivation of the drug and avoiding side effects such as digestive tract disorder which accompany oral administration. Generally, however, peptides or proteins show very poor mucosal absorbability and hence ordinary pharmaceutics for mucosal administration have the defect of failing to provide satisfactory high drug concentration in blood to exhibit the expected pharmaceutical efficacy.
Hence, various absorption enhancers to promote mucosal absorption of peptides or proteins have been studied and proposed. As organic acid type absorption enhancers, for example, salicylic acid or derivatives thereof KOKAI Patent Application Sho 56(1981)-122310(A) JP!, acidic amino acid or derivatives thereof KOKAI Patent Application Sho 56(1981)-138115(A) JP! and capric acid or salts thereof KOKAI Patent Application Sho 62(1987)-35(A) JP! are known. However, these mucosal absorption enhancers have the problems of being irritative to the mucosae and exhibiting yet insufficient mucosal absorption enhancing effect. Thus they are not fully satisfactory as mucosal absorption enhancers for peptides or proteins.
Furthermore, most of the pharmaceutics for rectal administration (which may be hereafter referred to as "suppository"), which is a form of mucosal administration, are formulated following the ordinary practice of uniformly dispersing and blending the drug as incorporated with an absorption enhancer in and with a suppository base. However, peptides or proteins are apt to cause such formulative problems when the ordinary method is adopted, as becoming unstable under the influences of absorption enhancer or suppository base or failing to provide a sufficient dose of rectal absorption because of insufficient release ability after administration. Thus, satisfactory pharmaceutics for rectal administration of the peptides or proteins have not yet been obtained.
Whereas, Kokai Patent Application Hei 1(1989)-313419(A) JP discloses a pharmaceutic for rectal administration in which a solid composed of the pharmacologically active ingredient and water-soluble macromolecules is uniformly dispersed in a fatty suppository base. The function and effect of the invention as disclosed in said Kokai Gazette, however, are to secure stable and good release of a pharmaceutically effective ingredient from the pharmaceutic irrelevantly to physical properties of the effective ingredient or those of the fatty suppository base. Hence the Gazette simply discloses the use of non-pH-dependent water-soluble macromolecules such as polyvinylpyrrolidone, macrogoal, and the like, stating nothing about promotion of rectal absorption of pharmaceutically active ingredient.
An object of the present invention is to provide pharmaceutics for mucosal administration exhibiting still improved mucosal absorption of pharmacologically active peptides or proteins.
Another object of the invention is to provide stable pharmaceutics for rectal administration exhibiting further improved rectal absorption of pharmacologically active peptides or proteins.